Is there any "quick" way to resolve a nested loop?

[Ikpefua Jacob-Obinyan]

Source: OUKC mock exams.
Hi Pals...Can any one advise me on the "quickest way" (if any) to resolve nested loops??, I burnt out toooo much time on them in my last two exams. I will appreciate your replies thanks.
Example:

 class Breakfast {
   public static void main(String[] args) {
     free:
     for(int j = 3; j > 0; j--) {
       for(int k = 0; k < 4; k++) {
         if(j == 1) break free;
         if(k == 2) break;
        System.out.print(" " + j + k);
       }
     }
   }
 }

A. 30 31 20 21
B. 30 31 32 20 21 22
C. 30 31 32 33 20 21 22 23
D. 30 31 32 20 21 22 10 11 12
E. 30 31 32 33 20 21 22 23 10 11 12 13
F. Compilation fails.

The answer is A. But like I said is there any "Short-Cut" to resolving this??.

[Matthew Brown]

There isn't really a short-cut. What I'd recommend is drawing a quick table. In this case you'd have three columns - j, k and output. Then just step through the program, writing out the values as they change. It really shouldn't take that long - took me about a minute when I tried it just now (a little longer to format it below, though!), and the exam gives you quite a bit more than that per question.

So you'd get something like this:

j  k  output
------------
3  0  " 30"
   1  " 31"
   2         - break
2  0  " 20"
   1  " 21"
   2         - break
1  0         - break free
END

[Ikpefua Jacob-Obinyan]

Matthew Brown wrote:There isn't really a short-cut. What I'd recommend is drawing a quick table. In this case you'd have three columns - j, k and output. Then just step through the program, writing out the values as they change. It really shouldn't take that long - took me about a minute when I tried it just now (a little longer to format it below, though!), and the exam gives you quite a bit more than that per question.

So you'd get something like this:

j  k  output
------------
3  0  " 30"
   1  " 31"
   2         - break
2  0  " 20"
   1  " 21"
   2         - break
1  0         - break free
END

Thank you very much Matthew, I am going to start practicing with this.

[Deepak Bala]

Matthew Brown wrote:There isn't really a short-cut. What I'd recommend is drawing a quick table. In this case you'd have three columns - j, k and output. Then just step through the program, writing out the values as they change. It really shouldn't take that long - took me about a minute when I tried it just now (a little longer to format it below, though!), and the exam gives you quite a bit more than that per question.

So you'd get something like this:

j  k  output
------------
3  0  " 30"
   1  " 31"
   2         - break
2  0  " 20"
   1  " 21"
   2         - break
1  0         - break free
END

This approach is pretty interesting. I usually maintain the value of the variables alone on paper for each run. At work this is never necessary since multiple nested loops and named blocks are rare.

[Ikpefua Jacob-Obinyan]

Deepak Bala wrote:

Matthew Brown wrote:There isn't really a short-cut. What I'd recommend is drawing a quick table. In this case you'd have three columns - j, k and output. Then just step through the program, writing out the values as they change. It really shouldn't take that long - took me about a minute when I tried it just now (a little longer to format it below, though!), and the exam gives you quite a bit more than that per question.

So you'd get something like this:

j  k  output
------------
3  0  " 30"
   1  " 31"
   2         - break
2  0  " 20"
   1  " 21"
   2         - break
1  0         - break free
END

This approach is pretty interesting. I usually maintain the value of the variables alone on paper for each run. At work this is never necessary since multiple nested loops and named blocks are rare.

@Deepak, I have been practicing this approach all day and it is REALLY interesting, like you said "At work" scenarios like these are RARE, but the SCJP exam organisers believe in "Good-Things-Dont-Come-Easy". Its left for us to take it OR leave it.

[Christian Joseph]

quick noobie question what does "free:" do?

[Henry Wong]

Christian Joseph wrote:quick noobie question what does "free:" do?

"free:" is a label. In this example, it is used to label the outer loop. The "break free" statement is used to break out of the labelled loop -- breaking out of two loops at the same time.

Henry

[Christian Joseph]

thanks Henry appreciate the reply

[Christian Joseph]

btw my answer is letter A

Btw what does the label do mr henry?

[Henry Wong]

Christian Joseph wrote:
Btw what does the label do mr henry?

Didn't my last response answer this question? If not, can you elaborate more on this question?

Henry